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Roots vs. Centrifugal

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Old Jun 23, 2002 | 05:48 PM
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From: Centrifugal City
Default Roots vs. Centrifugal

I'm considering the Magnuson blower for my C5.
Anyone want to help spell out the differences, adv/disadv of each type?

Would you rather have 8psi on a non-intercooled roots setup or 9-10psi on a dual-intercooled ATI setup? Considering your C/R is at 9.6:1

LPE seems to feel 5.5# non-intercooled is ok at 10.1 to 10.5:1, so I'd like to think I could squeak a bit more at 9.6:1

Should the roots by a stronger longer lasting charger too? I know it'll have more low and mid on-demand power. Just trying to come to a decision.. If I can get the Magnuson up to 8# or so and find a hood I like, I'm leaning that direction now. LPE seems to think it's a more reliable setup, but I'm not sure why.

Thx!

<small>[ June 23, 2002, 06:47 PM: Message edited by: MelloYellow ]</small>
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Old Jun 23, 2002 | 06:09 PM
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Default Re: Roots vs. Centrifugal

Wow, that's a tough call.

I know the 8#whipple on my friends Dakota felt pretty nice. He actually would pull me a little in my car if we started from his sweet spot but, once the little boost I had would start to build it was bye-bye to him.

The Magnuson will definately make more midrange but, the ATI should kill it on the top end. The intercoolers alone are probably worth 30-40hp assuming similiar boost.

I think the ATI will be nice on a 6speed. You can just select the right gear to put the engine in the right rpm range for the boost you want. The intercoolers are also a nice bonus.

If you had an automatic and didn't want to run a whole lot of stall or boost the Magnuson would be my choice.

Hard decision. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />

John
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Old Jun 23, 2002 | 06:46 PM
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From: Centrifugal City
Default Re: Roots vs. Centrifugal

I corrected the 1st post. Looks like there is an 8# pulley available! The 8# Eaton/Magnuson should have much higher average boost than a 9-10# ATI, eh? Average HP should be higher with lots more TQ, eh?
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Old Jun 23, 2002 | 06:47 PM
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Default Re: Roots vs. Centrifugal

That is a hard call. I would go for safety.. Intercoolers for me if I go that route..
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Old Jun 23, 2002 | 07:07 PM
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Default Re: Roots vs. Centrifugal

Average boost will be higher since you will see 8# of boost from ~3000rpm on up but, your hp/boost will be less with the magnuson and intake temps will be much higher. If you run a water/alky setup like SJH, intake temps are not a problem with an unintercooled setup.

This is just a guess but, I think you'll see 5psi around 4000rpm with a 9-10psi ATI.

The Eaton/Magnuson graph would probably look like a turbo graph as far as torque is concerned.(Lots of torque) <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

I'd say 8psi of unintercooled boost is pushing it even with 9.6:1 compression. Especially in the Florida heat. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

A water/alky setup may be mandatory with the Eaton and some extra insurance with the ATI in the Florida heat.

Each setup has its advantages and disadvantages and with the setups your looking at it makes this a very tough decision but, I'm still leaning towards the ATI.

John
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Old Jun 23, 2002 | 10:28 PM
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Default Re: Roots vs. Centrifugal

The Magna is a screw-type supercharger. The standard 6-71 blower are only 50% efficient. The Magna is anywhere from 80 to 90%. The higher the efficiency the less heat buildup of the pressure charge. That is why the Magna doesn't have an intercooler. The ATI unit is about 74% peak. The great thing about positive displacement superchargers (root or screw) is that they provide boost at lower RPMs than a dynamic supercharger (centrifical, excuse my spelling) which boosts at higher speeds. It depends on where you want the boost to be. I lean to the root because I perfer power at lower rpms, but you need to change the hood to get the blower to fit. The Procharger would be more covert setup and doesn't show any real power until you spin up the motor. Does this help?
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Old Jun 24, 2002 | 01:14 AM
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From: Centrifugal City
Default Re: Roots vs. Centrifugal

Yes, thanks! Thinking out loud mostly and more advice is great. I can definitely fall back on Water/Alky if I run into problems.

Looks like the Magnuson efficienct and less heat really helps. Keeping the timing under control, using LS1Edit, Widebands and Dyno.. keeping it rich.. Then again Water/Alky... If I can just find a hood I like, I think I'm sold!
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Old Jun 24, 2002 | 09:37 AM
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Default Re: Roots vs. Centrifugal

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">The Magna is a screw-type supercharger. The standard 6-71 blower are only 50% efficient. The Magna is anywhere from 80 to 90%. The higher the efficiency the less heat buildup of the pressure charge. That is why the Magna doesn't have an intercooler. The ATI unit is about 74% peak. </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">

No way is a magnacharger that efficient!
I took this off of their own website FAQ-

"I've heard roots superchargers are not efficient, how is the Magna Charger different?

Traditional roots blower design is old engineering, and admittedly is not very efficient, but engines designs from that era were not very efficient either. As engines have improved over the years so has roots supercharger design. The Magna Charger/Eaton supercharger is a hybrid-roots blower pump, with substantial design improvements. The rotors have a unique involute lobe shape and are engineered to a specific L ratio. Each rotor has been twisted 60 degrees to form a helix. The two counter rotating rotors have three lobes, which intermesh during operation. These twisted rotors, along with specially designed inlet and outlet port geometry, seal timing, and axial air flow help to reduce pressure variations resulting in a smooth discharge of air and a low level of noise during operation. This arrangement significantly improves efficiency over traditional roots superchargers and reaches a volumetric efficiency near 98%. Magna Charger applications have an adiabatic efficiency that stays above the 50% mark over the full operating range of the engine, from 2000 to 6000 rpm."

You may have confused volumetric efficiency with adiabatic efficiency.

Steve
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Old Jun 24, 2002 | 09:43 AM
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Default Re: Roots vs. Centrifugal

oh and it is NOT a screw type blower either.
The Whipple is, but not the magnacharger.
The magnacharger just has twisted rotors.
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Old Jun 24, 2002 | 10:36 AM
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Default Re: Roots vs. Centrifugal

The Magna Charger/Eaton supercharger is a hybrid-roots blower pump, with substantial design improvements. The rotors have a unique involute lobe shape and are engineered to a specific L ratio. Each rotor has been twisted 60 degrees to form a helix. The two counter rotating rotors have three lobes, which intermesh during operation. These twisted rotors, along with specially designed inlet and outlet port geometry, seal timing, and axial air flow help to reduce pressure variations resulting in a smooth discharge of air and a low level of noise during operation.

To me that sounds more like a screw-type design. There is less leakage around the lobes and moves air down the middle instead of the sides against the case. But in any event, boost and power is made at lower RPMs where street cruising is needed. If you want high RPM power, goto a Procharger.
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Old Jun 24, 2002 | 03:08 PM
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Default Re: Roots vs. Centrifugal

One thing people need to remember is that when you compress air its gonna get hotter. <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />

Here is what I can remember of the ideal gas law from school. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> I think there was a "n" in there somewhere but, it doesn't matter in this case.

P = Pressure(atmospheres)
V = Volume(Liters)
T = Temperature(Kelvin)

[(P¹V¹)/T¹] = [(P²V²)/T²]

Volume remains constant from inlet to outlet. So if P² is higher, T² is going to be higher also. There is no way around it. The addiabatic effeciency of the blower determines how much extra heat, above the heat from being compressed, is transfered to the outgoing air if I'm thinking about this right. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

There I go confusing myself again. I hated chemistry. <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" /> <img border="0" alt="[chug]" title="" src="graemlins/gr_chug.gif" />

With the Eaton/Magnuson you will need a very good tune and hope you never get a bad batch of gas if your going to run 8psi. The inlet air temps. are going to be disgusting if the air outside is 90-100°. If you want detonation get a diesel. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

Just thought I'd throw something else out there for ya to think about. <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />

John
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Old Jun 24, 2002 | 04:06 PM
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Default Re: Roots vs. Centrifugal

I'd like to see you do the Magnuson so you can tell us about it.

If you do it, I'll let you start 3 more new threads about lifter preload. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

I think the Magnuson will make gonzo torque but it's not what I would want for top end. But I'd like to try it for drag racing.
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Old Jun 24, 2002 | 04:49 PM
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Default Re: Roots vs. Centrifugal

Haha <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Ya, am seriously thinking about it. Do something different, u know..

Been talking to LPE, Magnuson and 2 aftermarket pulley manufacturers today. My logic right now, is.. If LPE can run this M112 Eaton at 5.5# with the Z06 10.5:1, I don't see why I can't squeak 8# at 9.6:1 with just programming.

Worst case scenario, I change my Windshield Wiper basin into an Alky/Water reservoir.

re: the top end, maybe the higher duration than stock will help the curve out up there.

re: the heat, ya, my main concern. Looks like it gets pretty bad the higher your RPM's go. Maybe I'll just shift lower RPM and advance the cam more, dunno.

<small>[ June 24, 2002, 06:19 PM: Message edited by: MelloYellow ]</small>
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Old Jun 24, 2002 | 05:01 PM
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Default Re: Roots vs. Centrifugal

Some links:
http://www.automotive.eaton.com/prod...rols/M112.html
http://www.magnuson-products.com/mp1...generation.htm
http://www.southfloridapulleyhq.com
http://www.powersurgeperformance.net/pulley_info.htm
http://www.atlantis.edu/~thepawn/lightning.html
http://www.caranddriver.com/xp/Caranddriver/features/2002/april/200204_sp ecialtyfile_lingenfelter.xml

<small>[ June 24, 2002, 06:18 PM: Message edited by: MelloYellow ]</small>
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Old Jun 24, 2002 | 06:19 PM
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Default Re: Roots vs. Centrifugal

bottom line:
the Roots type makes power Right Now, as opposed to the centrifugal type that has to spool up. <img border="0" alt="[Burnout]" title="" src="graemlins/burnout.gif" />
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Old Jun 24, 2002 | 07:55 PM
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Default Re: Roots vs. Centrifugal

It looks like the Delta in IAT will be 40* hotter than the LPE 5.5# setup at 10.1 or 10.5:1.

Think I can handle another 40* Temp increase at 8# at 9.6:1 ?? This is my main concern..
Plus I'm in S. Florida to begin with...

My Actual IAT's here avg 90-120*
The 5.5# adds another 80-120* + Florida 100* avg = around 200*
The 8# would be 120-160 + Florida 100* avg = around 240*

LOL, can 9.6:1 handle an effective 220-260* IAT at 8# with some ignition retard?? How does temp relate to how much timing we can run without detonating?? Any specifics?

The above leans me back to the ATI.

<small>[ June 24, 2002, 08:00 PM: Message edited by: MelloYellow ]</small>
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Old Jun 24, 2002 | 08:23 PM
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Default Re: Roots vs. Centrifugal

<img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

Holy Shiat!!

I'll have to check my service manual but, I think you'll be getting close to the limits of the IAT sensor. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

Water/Alky injection will be your only hope with those temps.

I don't think any amount of tuning can help with that.

One more <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> for good measure. <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />

John
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Old Jun 24, 2002 | 08:32 PM
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Default Re: Roots vs. Centrifugal

haha, ya.. looks pretty scary on paper huh?
<img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

But Lingenfelter is getting away with a 200* Air Charge temp on the Z06 10.5:1 ..? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

Maybe I should call the IAT actually the Air Charge Temp. Guess it'd still read a lower ambient at the IAT.

<small>[ June 24, 2002, 09:56 PM: Message edited by: MelloYellow ]</small>
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Old Jun 24, 2002 | 08:33 PM
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Default Re: Roots vs. Centrifugal

I'm telling ya.

Just put a Duramax diesel in there, run 20:1 compression, turn the boost up and don't worry about it. <img border="0" alt="[jester]" title="" src="graemlins/gr_jest.gif" />

John
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Old Jun 24, 2002 | 08:36 PM
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Default Re: Roots vs. Centrifugal

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MelloYellow:
<strong>haha, ya.. looks pretty scary on paper huh?
<img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

But Lingenfelter is getting away with 200* IAT's at the Z06 10.5:1 .. <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Well, Lingenfelter knows alot more about this stuff than I do. Call him up and see what he thinks. Those temps just seem outrageous to me.

If he thinks you can get away with it than do it.

It'll be one bad vette with an 8# magnuson on there. <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />
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